Two-stroke motor



Patented July 26, 1949 UNITED STATES PATENT OFFICE Application November5, 1945, Serial No. 626,771 In Belgium November 8, 1944 1 Claim.

This invention concerns improvements in two stroke motors for benzinewith carburettor operating according to the known system ofprecompression in the crank case.

This new construction is characterized thereby that:

(1) The overflow channels are constructed funnel-like, so that they Workas nozzles (diffusors), whereby during the scavenging greater speed ofthe gas mixture is obtained;

(2) The scavenging ports (outlet of the overflow channels into thecylinder) are arranged at .an angle of 90 with respect to the outlet, so

that the fresh gas when flowing over the piston into the cylinder isforced upwards at a determined angle, assuming thereby a fixed flowdirection and when striking the rounded compression-chamber returnsdownwards and then forces before itself the exhaust gases alreadyflowing outwards through the opened outlet port; as soon as the freshgas has about reached the outlet port the latter is already closed bythepiston moving upwards, so that very few or no fresh gas at all is lost;

(3) The scavenging ports are so arranged that at the beginning of thescavenging process, when the outlet is already open for some time andthe exhaust gases have thus assumed a certain flow direction, a counterflow with respect to the exhaust gases is induced and simultaneously bythe much cooler fresh gas warmth is withdrawn from the exhaust gases,whereby a steam shield is formed between the fresh gas and the exhaustgases, so that combustion of the fresh gas entering the cylinder isexcluded.

The invention will be described in the following by way of example inrelation with a two cylinder two stroke motor with reference to theaccompanying drawings, in which Figures 1 and 2 give axial sections ofthe cylinder at 90, whereas Figure 3 gives a transverse section of thecylinder, which clearly represents the position of the scavenging ports.Figure 4 is a section of one of the overflow channels in the cylinder.

The cylinder I is connected with the crank case 2, in which thepro-compression takes place. The piston 3 controls the inlet port 4, theoutlet port 5 and thescavenging ports 6, which are formed by the outletof the overflow channels. This outlet is shaped funnel-like so that thenarrowing gives rise to a diffusion effect for the gas mixture. Thescavenging ports 6 are thus arranged opposite to each other on eitherside of the axes of the inlet and outlet ports 4 and 5 at an angle of 90with respect to these axes.

The scavenging process is thus the following:

The gas mixture pro-compressed in the crank case 2 flows through the twooverflow channels 6 over the piston 3 into the cylinder I. These funnelshaped channels are so arranged that during the scavenging the gasmixture flows upwards at an angle, turns in a determined direction bystriking the compression chamber and then forces out before itself theexhaust gas through the outlet port 5. As soon as now the fresh gasmixture has almost reached the outlet port, the latter is closed by thepiston moving upwards, so that few or no fresh gas is lost during thescavenging. During the scavenging there is however still more or lessburning exhaust gas in the cylinder. Directly it flows into the cylinderthe much cooler fresh gas mixture withdraws warmth from the exhaust gascontained there; thereby and mainly due to the special position of theoverflow channels a shield 7 forms between the exhaust and the freshgas, whereby combustion of the fresh gas is prevented. Therewith theexact time of ignition is also in a narrow relation.

I claim:

In a two stroke engine of the class described, a cylinder, areciprocating piston in said cylinder, an inlet port leading into saidcylinder, an exhaust port leading from said cylinder, said exhaust portbeing diametrically opposite to said inlet port, scavenger channels, twoinclined scavenger passages in said cylinder, each said passage leadingfrom one of said channels and opening into said cylinder on each side ofsaid inlet port, the inclination of said passage with respect to a planeperpendicular to the axis of said cylinder being such that the axes ofsaid two passages meet at a point within said cylinder and remote fromthe top thereof, the axes of said passages being in a plane disposed atright angles to the axes of said inlet port and exhaust port and saidlast plane being located at a distance from said exhaust portpractically equal to the four fifths of the internal diameter of saidcylinder.

ANDRE IDE.

REFERENCES CITED The following references are of record in the 1c ofthis patent:

UNITED STATES PATENTS Number Name Date 1,632,988 Adams June 21, 19272,119,121 Steinlein May 31, 1933 2,189,357 Cull Feb. 6, 1940 FOREIGNPATENTS Number Country Date 646,031 France 1928 764,109 France 1934769,158 France 1934 441,668 Great Britain 1936 468,644 Great Britain1937 52,707 Denmark 1937 515,452 Great Britain 1939 847,369 France 1939

